The invention concerns a gap former in a paper machine, comprising a lower wire loop and a upper wire loop, which together define a substantially horizontal twin wire forming zone, which starts from the forming gap, which is confined in a space between the upper and the lower wire, this space becoming narrower so as to be wedge shaped, and in the area of which forming gap there is, inside the lower wire loop, a first forming roll, after the roll a forming shoe, after which, inside the lower wire loop, there are a number of dewatering members, after which the web is arranged to follow along with the lower wire, from which it is detached at the pick up point, being transferred onto a pick up fabric or equivalent.
With respect to the prior art most closely related to the present invention, reference is made to the U.S. Pat. Nos. 3,438,854, 3,996,098, and 4,056,433 as well as to the Published Finnish Patent Applications Nos. 61,217 and 77,702. Moreover, the prior art related to the present invention includes the former apparatus marketed by the Applicant under the trademark "SPEED FORMER HHS".RTM. (Appendix 1) and the former apparatus marketed by Messrs. Escher Wyss AG under the trademark "TWIN FORMER G".RTM., the latter one being described, e.g., in the journal Wochenblatt fur Papierfabrikation 11/12, 1989, p. 482, section 3.5.1 (Appendix 2).